Quota on UC admission

There is a quota for how many international students can be allowed to the UC's per year.
International students and out of state students pay 3 times more than local students.
In terms of income for the school, international and out of state students are preferred.
But because the UC's are public schools then local students, even if they pay less, have to be admitted.
To some degree, that's fair to promote diversity in the school environment.